Automated Emails from Shop to external domain emails not working with PS 9.0.2

[Joey]

We upgraded our site from 8.2.3 to 9.0.2 and ever since NO emails are getting through to customers. When we send a test email on the email page under advanced parameters it will only send to internal email addresses... external addresses do not received emails. We kept a backup of 8.2.3 and the emails send fine to external emails from the same page. The configuration is exactly the same.. we tested using SMTP and usr/bin mail and both work on 8.2.3 but not in 9.0.2

We're wracking our brains here... there's no errors and we can't find any logs with any errors. Customers aren't getting order confirmation, shipping confirmation or password reset emails etc.

If anyone has any insight it would be appreciated.

[ComGrafPL]

Any logs, that could show SMTP errors? 

[Joey]

There is no SMTP errors... Our 8.2.3 and 9.0.2 instances are on the same server and domain.  Everything works from 8.2.3 but not 9.0.2 with the same configuration.

[Fabry]

Mail templates missing?:-)

[Joey]

No... like we mentioned, everything works when sending emails to email addresses within our domain... it just doesn't send to external domains on 9.0.2 only.  It is still working fine on our 8.2.3 instance.  I guess we need to understand what changed between 8 and 9 that may have caused this

[Prestashop Addict]

I suppose you have reconfigured SMP settings... Did you try to send a test mail? In debug mode, noting in log?

[Joey]

Ok, so heres's the deal with this.  Apparently Prestashop moved from swiftmailer (with PS 8 ) to symfony mailer (with PS 9).  It appears that my host was blocking the new mailer from sending the emails externally.  We had to change our SMTP settings to a gmail server to get it to work.  We're not sure what changed between mailers, but this should not be a thing and needs to be looked at within Prestashop.  I've seen other people with the same issue.